Internal-combustion engines – Charge forming device – With fuel pump
Patent
1994-06-13
1995-06-27
Miller, Carl S.
Internal-combustion engines
Charge forming device
With fuel pump
123506, F02M 3704
Patent
active
054270731
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a so called unit injector for supplying fuel to a combustion chamber of an internal combustion engine, and of the kind comprising a body part to which is secured a fuel injection nozzle which defines an outlet orifice, a pumping plunger slidable within a bore in the body part, the plunger extending from one end of the bore and being movable inwardly into the bore to displace fuel from the bore to the injection nozzle, by an engine driven cam and a valve operable to control the amount of fuel delivered through the nozzle.
The object of the invention is to provide a unit injector of the kind specified in a simple and convenient form.
According to the invention in a unit injector of the kind specified an additional plunger is provided the additional plunger being slidable within and extending from the other end of the bore for actuation by a further engine driven cam.
An example of a unit injector in accordance with the invention will now be described with reference to the accompanying drawings in which:
FIG. 1 is a side elevation of the unit injector,
FIG. 2 is a view taken at right angles to FIG. 1, and
FIGS. 3 and 4 are views similar to FIG. 1 showing modifications.
Referring to FIGS. 1 and 2 of the drawings, the unit injector comprises a body part 10 from which extends a cylindrical screw threaded extension 11. Located in sealing engagement against the end face of the extension 11 is one end of a cylindrical distance member 12 against the other end of which is located in sealing relationship, a distance piece 13A against which is located a fuel injection nozzle 13. The injection nozzle body, the distance piece 13A, the distance member 12 and the extension 11 are held in assembled relationship by means of a cap nut 14.
The fuel injection nozzle 13 includes the nozzle body and a valve member (not shown) which is slidable within the nozzle body in known manner. The valve member defines an annular area against which fuel under pressure can act to lift the valve member from a seating thereby to allow fuel flow through an outlet orifice formed in the tip 15 of the nozzle body.
Movement of the valve member of the nozzle under the action of the fuel pressure is opposed by the action of a spring 16 which is housed within a chamber 17 formed in the distance member 12. The inner end of the chamber communicates byway of a drilling 18 with an annular fuel inlet chamber 19 which is disposed between the exterior surface of the distance member and the inner surface of the cap nut and the chamber communicates by way of inlet openings 20 formed in the wall of the cap nut 14, with a fuel supply gallery defined by the wall of the bore in the cylinder head of the engine in which the injector is located. A fuel filter 20A surrounds the openings.
Formed in the body part 10 is a transverse bore 21 the axis of which extends in a plane at right angles to the axis of the extension 11 and mounted in the bore is a pair of pumping plungers 22 which extend outwardly from the opposite ends of the bore. The plungers are coupled to a pair of tappets 23 respectively and the tappets 23 are of cylindrical form and are slidable within hollow guide sleeves 24 which are integrally formed with the body part 10. The tappets carry rollers 25 respectively for engagement with cams 26 mounted on contra rotating cam shafts of the associated engine. The cam shafts mount additional cams for operating the inlet and exhaust valves of the engine.
The connection between the plunger and its associated tappet is of the T slot variety and is deliberately slack to minimise the possibility of any side thrust being imposed on the plungers. The tappets are biased outwardly by means of coiled compression springs 27 which by virtue of the form of connection between the plungers and the tappets also urge the plungers outwardly.
In order to prevent rotation of the tappets each guide sleeve 24 is provided with a circular opening in which is located a ball 29 which rides in a groove 30 formed in the tappet body. The balls 29 also act to prevent
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patent: 2019650 (1935-11-01), Bischof
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patent: 2396602 (1946-03-01), Posch
patent: 4505245 (1985-03-01), Lintott
patent: 4615323 (1986-10-01), LeBlanc
patent: 4714066 (1987-12-01), Jordan
patent: 5007401 (1991-04-01), Grohn
Lintott Edward R.
Timms Colin T.
Lucas Industries Public Limited Company
Miller Carl S.
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